Fix missing file extension on sub URL imports

package.json

@@ -1,6 +1,6 @@
 {
    "name": "@hibas123/jrpcgen",
-   "version": "1.2.11",
+   "version": "1.2.12",
    "main": "lib/index.js",
    "license": "MIT",
    "packageManager": "yarn@3.1.1",

src/process.ts

@@ -18,7 +18,7 @@ import { ZIGTarget } from "./targets/zig";
 import { DartTarget } from "./targets/dart";
 import { URL } from "url";
 
-class CatchedError extends Error {}
+class CatchedError extends Error { }
 
 const log = dbg("app");
 
@@ -53,6 +53,9 @@ function resolve(base: string, sub?: string) {
    } else if (base.startsWith("http://") || base.startsWith("https://")) {
       let u = new URL(base);
       if (sub) {
+         if (!sub.endsWith(".jrpc")) {
+            sub += ".jrpc";
+         }
          u = new URL(sub, u);
       }
       return u.href;